全文获取类型
收费全文 | 239篇 |
免费 | 38篇 |
专业分类
林业 | 1篇 |
基础科学 | 5篇 |
25篇 | |
综合类 | 50篇 |
农作物 | 16篇 |
水产渔业 | 16篇 |
畜牧兽医 | 148篇 |
园艺 | 6篇 |
植物保护 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 14篇 |
2007年 | 14篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1942年 | 2篇 |
1940年 | 2篇 |
排序方式: 共有277条查询结果,搜索用时 515 毫秒
41.
Riegel CM Stockham SL Patton KM Thomas CL 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2008,37(3):353-356
Pleural effusion was examined from a 5-year-old, female Brittany Spaniel with a 7-day history of dyspnea, anorexia, and diarrhea. The fluid was yellow, cloudy, and slightly gelatinous, and had a total protein concentration of 2.8 g/dL, a total nucleated cell concentration of 1.1 x 10(3)/muL, and a triglyceride concentration of 177 mg/dL. A cytocentrifuged preparation contained a mixed inflammatory cell population with a predominance of small lymphocytes and abundant mucinous material in the background. The dog died 3 days later and a mass was found within the lumen and wall of the right auricle of the heart at necropsy. Histopathologic sections of the mass contained a population of anaplastic spindle cells diffusely suspended in a pale basophilic matrix, consistent with myxosarcoma. The cells were positive for vimentin and negative for cytokeratin, desmin, and von Willebrand factor VIII-related antigen. A myxoid matrix was confirmed by positive staining with Alcian blue. Myxosarcoma is a rare cardiac tumor in dogs that should be considered, along with mucus-producing carcinomas and bile, as a cause of muculent effusion. 相似文献
42.
43.
Are extinctions of marine vertebrates as rare and unlikely as current data indicate? Long-term research surveys on the continental shelf between the Grand Banks of Newfoundland and southern New England reveal that one of the largest skates in the northwest Atlantic, the barndoor skate (Raja laevis), is close to extinction. Forty-five years ago, research surveys on St. Pierre Bank (off southern Newfoundland) recorded barndoor skates in 10% of their tows; in the last 20 years, none has been caught, and this pattern of decline is similar throughout the range of the species. 相似文献
44.
RL Westemeier JD Brawn SA Simpson TL Esker RW Jansen JW Walk EL Kershner JL Bouzat KN Paige 《Science (New York, N.Y.)》1998,282(5394):1695-1698
Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens. 相似文献
45.
46.
Jann Th. Martinsohn Paul Raymond Trey Knott Kevin A. Glover Einar Eg Nielsen Lars Bonde Eriksen Rob Ogden John Casey Jordi Guillen 《Fish and Fisheries》2019,20(2):391-401
Evidence from DNA‐analysis is commonplace in human criminal investigations, and while it is increasingly being used in wildlife crime, to date, its application to control and enforcement activities in fisheries and aquaculture has only been sporadic. Contemporary DNA‐analysis tools are capable of addressing a broad range of compliance issues, species identification, mislabelling of fish products, determining the origin of catches and the farm of origin of aquaculture escapees. Such applications have the potential to ensure traceability along the fish product supply chain and to combat consumer fraud and Illegal, Unreported and Unregulated fishing. Nevertheless, DNA‐analysis is not yet used routinely in investigations into compliance with fisheries and aquaculture legislation. One potential reason for this is that DNA‐analysis techniques may have been regarded as too expensive. However, costs have plummeted over the past decade prompting us to objectively assess whether the costs associated with routine use of DNA‐analysis techniques for fisheries and aquaculture control and enforcement activities do constitute an impediment. Based on a number of recent fisheries and aquaculture compliance investigations that incorporated DNA‐analysis, our results indicate that the use of genetic analysis was justified and worthwhile in all cases examined. We therefore conclude that the costs associated with DNA‐analysis do not represent a barrier to the routine adoption of DNA‐analysis techniques in fisheries and aquaculture compliance investigations. Thus, control and enforcement agencies should be encouraged to use such techniques routinely. 相似文献
47.
Abscisic acid (ABA) is crucial in fruit maturation and senescence and is considered as the other ripening control factor other than ethylene. Important components in ripening fruit are soluble sugars, which make the fruit sweeter and carotenoids, important flavor compounds in ripened fruit. The purpose of this study was to examine the effects of foliar ABA and calcium (Ca) fertilizer treatments (individually and in combination) on determinate beef-steak greenhouse tomato (Solanum lycopersicum) leaf chlorophylls and carotenoids, fruit carotenoids, and soluble sugar concentrations. Foliar spray treatment of 500 mg L?1 ABA increased zeaxanthin (ZEA) and β-carotene (BC) in tomato leaf tissue. Increases in Ca fertilizer treatments significantly decreased tomato leaf violaxanthin (VIO), but no effect on other carotenoids. The application of 500 mg L?1 ABA foliar spray significantly increased glucose and fructose concentrations in tomato fruit tissue. Foliar application of ABA treatments can increase overall chlorophyll, carotenoid content, and fruit quality. 相似文献
48.
49.
50.
Craig A. Kiebler Lyndsay Bottichio Latoya Simmons Colin Basler Rachel Klos Nikos Gurfield Elizabeth Roberts Akiko Kimura Linda S. Lewis Kiyomi Bird Felicia Stiles Linda K. Schlater Kristina Lantz Thomas Edling Casey Barton Behravesh 《Zoonoses and public health》2020,67(4):425-434
Reptiles are one of the fastest growing sectors in the United States pet industry. Reptile‐associated salmonellosis (RAS) continues to be an important public health problem, especially among children. We investigated an outbreak of human Salmonella infections resulting from serotypes Cotham and Kisarawe, predominately occurring among children. An outbreak of illnesses was identified in persons with exposure to pet bearded dragon lizards. Human and animal health officials, in cooperation with the pet industry, conducted epidemiologic, traceback and laboratory investigations. Onsite sampling was conducted at two US breeding facilities, one foreign breeding facility, and a large pet retail chain. A total of 166 patients in 36 states were identified with illness onset dates from 02/2012–06/2014. The median patient age was 3 years (range, <1–79 years), 57% were aged ≤5 years, and 37% were aged ≤1 year. Forty‐four patients (37%) were hospitalized, predominantly children. Sampling at breeding facilities and a national pet store chain resulted in isolation of outbreak serotypes at each facility; isolation proportions ranged from 2%–24% of samples collected at each facility.Epidemiologic, microbiologic and traceback evidence linked an outbreak of uncommon Salmonella serotypes to contact with pet bearded dragons. The high proportion of infants involved in this outbreak highlights the need to educate owners about the risk of RAS in children and the potential for household contamination by pet reptiles or their habitats. Strategies should be developed to improve breeding practices, biosecurity and monitoring protocols to reduce Salmonella in the pet reptile trade. 相似文献